1. Field of the Invention
The present invention relates to a new and improved design of a shock absorption structure for a treadmill, and more particularly, to a structure which utilizes two connecting arms and two flexible shock absorption units. Each of the flexible shock absorption units is pivotably interposed between an extension member of the handle frame and the connecting arm. Therefore, when the force is applied to the frame portion, both flexible shock absorption units provide proper cushioning effect. Moreover, the flexible shock absorption unit is constructed in such a way that the cushioning force can be freely adjustable so as to enhance the using comfort.
2. Description of the Prior Art
In general, the treadmill is provided with cushioning apparatuses at suitable places for achieving a proper cushioning effect and enhancing the comfort of the operator during a workout session. Meanwhile, a protection mechanism has been developed for preventing both feet of the operator from being injured due to the too large reactive force of the platform of the treadmill. It will be particularly beneficial to the operator if hydraulic or pneumatic cylinders are used to provide more excellent cushioning effect. A few prior arts such as U.S. Pat. Nos. 4,591,147, 5,184,988, 4,974,831, 4,984,810, 5,072,928, 5,372,559, etc. have disclosed the application of hydraulic or pneumatic cylinders to the treadmill.
Although the above-mentioned prior arts have advantages of more excellent protection effect and greater comfort, they all don't have any automatic mechanism for adjusting the cushioning force by operators themselves to meet their own different requirements. In brief, a operator with heavier weight would feel that the cushioning force is too slight while a operator with lighter weight could feel that it is too strong if the cushioning force is fixed at a certain extent. Besides, different operators are their own subjective feeling about the cushioning strength no matter how strong or light the cushioning force is. In addition, some operators have special rehabilitation requirements thereto. Accordingly, the prior arts are required for improvement.